Methylphenidate extended release chewable tablet

ABSTRACT

An oral methylphenidate extended release tablet is described, which can be scored and still retain its extended release profile. The tablet contains a combination of an uncoated methylphenidate-ion exchange resin complex, a barrier coated methylphenidate-ion exchange resin complex-matrix, and an uncomplexed methylphenidate active component. Following administration of a single dose of the extended release methylphenidate chewable tablet, a therapeutically effective amount of methylphenidate is reached in less than about 20 minutes and the composition provides a twelve-hour extended release profile.

BACKGROUND OF THE INVENTION

Methylphenidate hydrochloride (HCl) and dexmethylphenidate hydrochloride both have the empirical formula C₁₄H₁₉NO₂.HCl. Methylphenidate HCl is a racemic mixture of d,l-threo-methyl α-phenyl-2-piperidineacetate hydrochloride. Several commercial products, including, e.g., Ritalin®, Daytrana™, and Metadate™ contain methylphenidate HCl as the active drug. Dexmethylphenidate is the d-threo-enantiomer of racemic methylphenidate hydrochloride [Focalin® product literature]. There are several commercial products which contain dexmethylphenidate as the active drug.

The use of the central nervous system stimulants methylphenidate and dexmethylphenidate for the treatment of such conditions as attention deficit disorder (ADD) and attention deficit hyperactivity disorder (ADHD) in adults and children has been described [see, Focalin®, Concerta®, Daytrana™ and Metadate® product literature]. This drug may also be used to treat depression and cognitive impairment following Traumatic Brain Injury [See, product literature for methylphenidate hydrochloride tablet which is commercially available from Lake Erie Medical DBA Quality Care Products LLC, and product literature of the other drug products identified herein].

Solid dose methylphenidate or dexmethylphenidate products are commercially available having an extended release profile of 8 hours according to the product label. These products include, e.g., Ritalin® LA and Methylin® ER tablets have product labels indicating that they must be swallowed whole without crushing or chewing. Liquid methylphenidate dosage forms have also been described which are predominantly designed for children, including children as young as 3 years old who have difficulty swallowing solid dosage forms.

There remains a need for a quick-acting, stable, extended release methylphenidate product which can be conveniently delivered in a form suitable for patients who have difficulty swallowing solid tablets and capsules.

SUMMARY OF THE INVENTION

The present invention provides a methylphenidate extended release chewable tablet which provides a fast onset of MPH and a twelve-hour release profile. The chewable tablet can be divided into portions and these tablet portions retain the fast onset and 12 hour release profile of the intact tablet. In one embodiment, the tablet is scored to facilitate splitting when desired. Methods of treating patients in need thereof with these methylphenidate (MPH) extended release chewable tablets are further provided by the invention.

The MPH extended release chewable tablet comprises (i) two different immediate release methylphenidate components, each of which provides a different immediate release profile, and (ii) about 50% to about 90% w/w of a sustained release barrier coated methylphenidate-ion exchange resin complex-matrix, based on the total weight of the methylphenidate components.

The first immediate release methylphenidate components is an uncoated methylphenidate-ion exchange resin complex, optionally in combination with a matrix forming polymer which is characterized herein as the “slower” onset immediate release component. The second immediate release component is a faster onset immediate release methylphenidate component which is a methylphenidate, pharmaceutically acceptable salt thereof, or hydrate thereof as defined herein, which is not complexed with or bound to an ion exchange resin. The sustained release component has a barrier coating which is a pH-independent release, high tensile strength, water insoluble, water-permeable barrier coating.

In another embodiment, the invention provides a scored chewable tablet, wherein dividing the tablet does not significantly modify the in vitro profile of the tablet portions resulting from split or other division of the intact tablet.

In one embodiment, a methylphenidate extended release chewable tablet comprises methylphenidate components in a combination of (a) about 60% w/w-80% w/w of a sustained release, cured, barrier coated methylphenidate-ion exchange resin complex-matrix, wherein the barrier coating comprises polyvinylacetate and a plasticizer (b) about 10% w/w to about 20% w/w of a combination of an immediate release uncoated methylphenidate-ion exchange resin complex and (c) about 10% w/w to about 20% w/w of an immediate release uncomplexed methylphenidate. Throughout this specification, when weight percentages and/or ratios are provided for methylphenidate in each of the three active components, the weights are based on the amount of methylphenidate base in each component. As used herein the term “uncomplexed methylphenidate” is referred to as the faster onset immediate release component and specifically includes a free base methylphenidate, as well as a pharmacologically active and physiologically compatible salt form thereof, including acid addition salts, and hydrates thereof; specifically excluded from the term “uncomplexed methylphenidate” is a methylphenidate which bound to or complexed with an ion exchange resin.

In a further embodiment, the invention provides a method of treating patients with a disorder for which methylphenidate is regulatory approved by administering a methylphenidate extended release chewable tablet as described herein.

Still other aspects and advantages of the invention will be apparent from the following detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a linear plot of mean methylphenidate plasma concentration versus time using non-transformed data. This study provides the pharmacokinetic (pK) profile of a single oral chewable tablet formulation of the invention dosed as described in Example 2 to provide an amount of methylphenidate equivalent to a 40 mg dose of methylphenidate HCl. A commercially available immediate release methylphenidate HCl tablet (Methylin® 10 mg chewable tablet, 2×20 mg delivered six hours apart (q6h)) was used as reference.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect the invention provides a methylphenidate (MPH) extended release chewable tablet. The MPH contains a combination of two different immediate release MPH components and a sustained release MPH component. Suitably, following administration of a single dose of the oral MPH extended release chewable tablet, in some embodiments, a therapeutically effective amount of MPH is reached in less than about thirty minutes, and as soon as about twenty, ten, or fewer minutes, and the formulation provides an extended release profile to at least about 12 hours.

The MPH extended release chewable tablets of the present invention are typically prepared as single uniform solid dispersion compressed into a chewable tablet. Suitably, the chewable tablet of the invention is a uniform solid dispersion which provides extended release properties even when scored such that when divided the separated tablet portions retain the extended release profile described herein. In one embodiment, the chewable tablet has a hardness of about 5 kilopond (kp) to about 25 kp, about 8 to about 20 kp, or 10 to about 16 kp. One (1) kilopond is one kilogram of force (kgf). Newtowns (N) are the SI unit of force and the SI standard for tablet hardness testing. 1 kilopond (kp) is equal to 9.80665 Newtons (N). Presented in Newton rounded to the nearest five, the chewable tablet has a hardness of about 45 N to about 245 N, about 75 N to about 200 N, or about 95 N to about 160 N. Optionally, the hardness may be dose proportional, with lower doses having lower hardness levels. For example, a 20 mg chewable tablet may have a hardness in the range of about 10 to about 12 kp (about 98 N to about 118 N), a 30 mg tablet may have a hardness in the range of about 12 to about 14 kp (about 118 N to about 137 N), and a 40 mg tablet may have a hardness in the range of about 14 kp to about 16 kp (about 137 N to about 156 N). In one embodiment, the hardness is determined following compression and prior to application of any color or other non-functional tablet coating as defined herein. In one embodiment, the tablet portions meet the USP Friability requirement. In one embodiment, the friability of both the intact tablet and the tablet portions are less than about 1.

A chewable tablet of the invention is distinguished from a rapid dissolve tablet or an orally dissolving tablet (ODT) by not dissolving in the mouth in less than 1 minute, and more generally, not breaking apart or dissolving in the oral cavity in less than about 3 to about 5 minutes without being chewed.

As used herein “methylphenidate” includes the free base form of the active ingredient which is either (i) racemic mixture of two optical isomers d-threo-methylphenidate and 1-threo-methylphenidate or (ii) the active isomer d-threo-methylphenidate (also known as dexmethylphenidate). For convenience, methylphenidate is abbreviated “MPH” herein. When reference is made herein to methylphenidate or MPH, it will be understood that either the racemic mixture (typically 50/50 d- to l-) or dexmethylphenidate is encompassed by this term. Where only the racemate or dexmethylphenidate is desired, reference will be specifically made to one or the other. Thus, for the formulations described herein, the methylphenidate may be independently selected from racemic methylphenidate (e.g., a 50/50 mixture of D-methylphenidate and L-methylphenidate), and dexmethylphenidate. Whether selected from the racemate or dexmethylphenidate, the active drug may be present in the form of a salt or a hydrate. One suitable salt is the HCl salt form. However, other salts may be selected, e.g., the acetate salt, the maleate salt or any other pharmaceutically acceptable acid addition salt. Methylphenidate may be purchased commercially, e.g., as the hydrochloride salt thereof. Alternatively, the MPH may be prepared using methods known to those of skill in the art. Processes for the synthesis of methylphenidate and its analogs have been described. See, e.g., WO 2010/080787; U.S. Pat. Nos. 2,507,631 and 2,957,880, as have processes for synthesis of threo-methylphenidate and its d-enantiomer have been reported and which are incorporated herein by reference. See, e.g., US Patent Application Publication No. 2006/0135777, which is incorporated herein by reference.

As used herein, the term “free methylphenidate” refers to the weight of the methylphenidate base, i.e., exclusive of any salt or complex form.

In one embodiment, a MPH extended release chewable tablet the invention contains a methylphenidate in three different forms, (a) a sustained release barrier coated MPH-ion exchange resin complex, optionally in a matrix, (b) an slower onset immediate release uncoated MPH-ion exchange resin complex, optionally in a matrix, and (c) a faster onset immediate release uncomplexed MPH. While the source of the MPH in the working examples herein was the same, it will be understood that the MPH can be independently selected for each of component (a), (b) and (c). For example, the complexes of each (a) and (b) may be produced using the same MPH (e.g., racemic MPH) and (c) may be a different MPH (e.g., dexMPH). Alternatively, the complexes of each of (a) and (b) may be produced using different MPH and the MPH of (c) may be independently selected.

As used herein, the term “extended release” (“ER”) refers to compositions which are characterized by having at least one of the active components (i.e., MPH or dexMPH) having a release over a period of at least about 12 hours. As with formulations described herein, “extended release” may be achieved by a single formulation containing two “immediate release” components and a “sustained release” (i.e., release for about 12 hours). The release profile may be assessed via in vitro dissolution using techniques known to those of skill in the art [e.g., USP basket method, Paddle Method, channel flow method, or other methods known in the literature]. The release profile can be assessed in vivo (e.g., for bioavailability determinations), using plasma concentrations to assess maximum plasma concentration (C_(max)) and area under the curve (AUC). Such assays are well known to those of skill in the art. [see, e.g., W. Wargin, et al., Pharmacokinetics of methylphenidate in man, rat and monkey. J Pharmacol Exp Ther August 1983 226:382-386].

The term “immediate release” (“IR”) is the release of an active ingredient (e.g., MPH) from a pharmaceutical formulation where the rate of release of the active pharmaceutical ingredient from the pharmaceutical formulation is not retarded by means of a controlled release matrix or other such means and where the components of the pharmaceutical formulation are designed such that, upon ingestion, maximum exposure of said active pharmaceutical ingredient to body tissues occurs in the minimum period of time. As described herein, an “immediate release” MPH component preferably releases in less than 1 hour. The present invention provides for an extended release chewable tablet having two different immediate release MPH components, each of which provides a different release profile.

Suitably, one of the immediate release components provide a faster onset, i.e., release and therapeutic effect in less than 30 minutes, preferably, less than 20 minutes and in as few as ten minutes, or sooner. This immediate release component is an uncomplexed MPH which is defined in the specification. A second, different, immediate release component provides a different immediate release pharmacokinetic profile, which releases in less than about an hour, as soon as about 45 minutes, or as soon as about 30 minutes. Typically, this immediate release component does not release as quickly as the faster onset component. Suitably this slower onset immediate release component is an uncoated MPH-ion exchange resin complex, which is optionally in a matrix with a matrix forming polymer. When present in the immediate release component, the matrix forming polymer is selected so that the resulting uncoated MPH-ion exchange resin complex (optionally in a matrix) retains an immediate release profile. For convenience, the optional matrix is not referenced in every phrase where the uncoated complex is discussed. However, it will be understood that this uncoated complex may contain such a component. The release profiles of the two different immediate release components may overlap.

In one embodiment, the faster onset immediate release component (uncomplexed MPH) releases almost 100% of the MPH within about the first twenty to thirty minutes following administration. In another embodiment, the slower onset immediate release uncoated MPH-ion exchange resin complex releases at least about 50% of the MPH within about the first hour following administration, and at least about 80% of the MPH within about 90 minutes following administration.

In one example, the sustained release barrier coated MPH-ion exchange resin complex, optionally in a matrix is present in an amount of about 50% w/w to about 90% w/w, about 60% w/w to about 80% w/w, or about 68 w/w to about 72% w/w of the MPH components in the chewable tablet. The two immediate release components combine to provide about 10% w/w to about 50% w/w, about 20% w/w to about 40% w/w, or about 25% w/w to about 30% w/w of the MPH components in the chewable tablet. The uncoated MPH-ion exchange resin complex component is designed to be immediate release as defined herein, and as such, does not contain a coating which functions to delay release (e.g., no functional amount of an extended release barrier coating or enteric coat). Suitably, immediate release MPH-ion exchange resin complex is present in an amount of about 5% w/w to about 30% w/w, or about 10% w/w to about 20% w/w, of the MPH components in the chewable tablet. The extended release component and the immediate release MPH-ion exchange resin complex are further in combination with an uncomplexed MPH drug. The other IR component, which is uncomplexed MPH drug, is present in an amount of about 5% w/w to about 30% w/w, or about 10% w/w to about 20% w/w, of the MPH components in the chewable tablet. In one embodiment, the weight percentages of MPH contributed by each of the two immediate release components are the same. However, in other embodiments, it may be desirable to provide MPH in the immediate release components in different weight percentages.

When expressed as a ratio, the ratio of the two immediate release components comprise MPH in a ratio of uncoated MPH-resin complex (optionally in a matrix) to that in uncomplexed methylphenidate in the chewable tablet is generally in the range of about 6:1 (uncoated MPH complex:uncomplexed MPH) to about 1:6 (uncoated MPH complex:uncomplexed MPH), or about 2:1 to about 1:2. In one embodiment, the ratio of extended release coated MPH-resin complex to uncoated MPH complex is in the range of about 18:1 (coated MPH:uncoated MPH complex) to about 5:3 (coated MPH complex:uncoated MPH complex), or about 8:1 to about 3:1.

In one embodiment, the ratio of MPH in coated MPH-resin complex:uncoated MPH-resin complex:uncomplexed MPH is 80:10:10 to about 70:15:15. However, other suitable ratios, including those in which the MPH in the two immediate release components differ from each other, may be selected within the ranges provided herein.

The term “initial administration” is defined for purposes of the present invention as the first single dose of a formulation containing an active ingredient administered to a patient or subject or the first dose administered to a patient or subject after a suitable washout period.

As is often the case with psychoactive drugs, a therapeutic result for MPH is not solely related to plasma levels of the drug. Thus, “a therapeutically effective amount” of MPH includes the minimum amount of the drug required to provide a clinically observable psychological and/or behavioral response. A therapeutically effective amount of MPH can alternatively be defined as being at least the minimum amount of MPH which reduces or eliminates the symptoms associated with a condition for which MPH has been approved for use. Appropriate doses are discussed in more detail later in this specification.

Additionally, because the chewable MPH tablet described herein retains its extended release properties even when scored. Further, even following being divided into other suitable portions, it is convenient for physicians to reduce the dose for patients to introduce the drug in a smaller dose or incremental doses of medication for patients whose needs dictate such. This ability to divide the dose into portions allows physicians to take into consideration individual patient needs, including factors like age, body weight and individual response to the medication without the need for taking multiple doses over a twelve hour period of another product which offers only immediate release.

A “methylphenidate-ion exchange resin complex” refers to the product resulting from loading a methylphenidate salt onto a cation exchange resin. Methods for preparing such complexes have been described, e.g., in WO 2007/109104, incorporated herein by reference. This describes the complexation which occurs when the active and the ion exchange resin are mixed together in an aqueous medium to facilitate the “exchange” between the salt of the MPH and the “cation” of the ion exchange resin and the formation of the complex, which may be referred to as “methylphenidate polistirex”.

WO 2007/109104 also describes polyvinylacetate-based barrier coatings which are particularly well suited for use in the formulations described herein to provide a sustained release coat over the MPH-ion exchange resin complex-matrix. However, one skilled in the art can select other barrier coatings to provide the sustained release characteristics to MPH-ion exchange resin complex-matrix.

As used herein, a “precoated” MPH-ion exchange resin complex or a “precoated” MPH-ion exchange resin complex-matrix refers to a particle which is to be subsequently coated with a barrier coating as defined herein. In some embodiments, where the MPH-ion exchange resin or MPH-ion exchange resin complex-matrix is to be used as one of the immediate release components and no barrier coating is to be applied, it is referred to as “uncoated”.

As used herein, a barrier coat is a water-permeable, water-insoluble, pH-independent polymer or co-polymer which in the present invention confers sustained release to the coated MPH-ion exchange resin complex-matrix. In one embodiment, the barrier coat is pH-independent, non-ionic and is applied, e.g., as an aqueous suspension, over the precoated MPH-ion exchange resin complex-matrix and forms a separate layer thereon. In another embodiment, the barrier coat is pH-independent, non-ionic and is applied as a solvent-based coating, over the precoated MPH-ion exchange resin complex-matrix and forms a separate layer thereon. In still another embodiment, the barrier coat is pH-independent, ionic and is applied over the precoated MPH-ion exchange resin complex-matrix to form a separate layer thereon. Preferably, the barrier coat is directly over the precoated MPH-ion exchange resin complex-matrix and the barrier coat layer, i.e., there are no intervening layers between the barrier coat and the precoated MPH-ion exchange resin complex-matrix. Depending upon the polymeric material selected, the barrier coat polymer or co-polymer may be cured to maximize their properties depending on the barrier coating selected. These polymers and their curing requirements are discussed in more detail elsewhere in this specification.

A “methylphenidate-ion exchange resin complex-matrix” refers a MPH-ion exchange resin complex which is further combined, e.g., prior to or during granulation, with a polymeric material which forms a matrix with the MPH-ion exchange resin complex.

In one embodiment, a “methylphenidate polistirex” refers to the complex formed by loading a methylphenidate onto or reacting a methylphenidate with an ion exchange resin. This term and the term “MPH-ion exchange resin complex” may be used interchangeably throughout this document.

The term “matrix forming polymer” or “matrix forming polymeric material” refers to both water-insoluble polymers/co-polymers and water-soluble polymers/co-polymers which form a matrix with the MPH-ion exchange resin complex upon being admixed or granulated therewith. Suitably, the matrix forming polymer is non-reactive with the MPH and the ion exchange resin. The matrix forming polymer may be a water-insoluble polymers/co-polymers and polymer systems which have been described as release retardants [see, e.g., polymers discussed in U.S. Pat. No. 8,062,677, incorporated herein by reference], and those hydrophilic polymer systems which have been described in the literature as impregnating or solvating agents [see, e.g., polymers discussed in U.S. Pat. No. 8,062,677 and U.S. Pat. No. 4,221,778, incorporated herein by reference]. In one embodiment, a MPH-ion exchange resin complex-matrix may include more than one matrix-forming polymer system. For example, an MPH-ion exchange resin complex-matrix may contain both a hydrophilic polymer and a hydrophobic polymer. An immediate release “uncoated methylphenidate-ion exchange resin complex” may optionally be in a matrix. In this instance, the matrix forming polymer does not alter the ability of component to provide an immediate release profile. For example, a polyvinylpyrrolidone may be selected. However, the matrix forming polymer may alter the release rate of this complex while still maintaining an immediate release profile as defined herein.

The following terms are used in the specification and are to be interpreted in accordance with the definitions herein.

“C_(max)” is the maximum observed plasma concentration, calculated as the geometric mean of the individual maximum blood plasma concentrations.

The term “mean maximum plasma concentration” (mean C_(max)) is defined for the purposes of the present invention as the maximum mean plasma drug concentration.

“Mean plasma concentration” is the geometric mean blood plasma concentration.

The term “T_(max)” is the time at which the peak (maximum) observed blood plasma drug concentration for each individual participating in the bioavailability study.

The term “AUC_(0-∞)” or “AUC_(inf)” is the mean area under the plasma concentration-time curve extrapolated to infinity. It is calculated as the arithmetic mean of the area under the plasma concentration-time curve from time 0 extrapolated to infinity, calculated for each individual participating in the bioavailability study.

AUCpR is the area under the curve to the population median T_(max) of the reference formulation. AUC_(0-t) is the area under the plasma/serum/blood concentration-time curve from time zero to time t, where t is the last time point with measurable concentration for individual formulation.

T/R ratio refers to the test formulation (MPH ER chewable tablet (40 mg) to reference (R) formulation (Methylin® IR 10 mg chewable tablet).

Intra-subject CV % refers to the geometric (CV) coefficient of variation between subjects.

The term “half-life” is the apparent terminal elimination half-life (T_(1/2)).

The words “comprise”, “comprises”, and “comprising” are to be interpreted inclusively rather than exclusively. The works “consist”, “consisting”, and its variants, are to be interpreted exclusively, rather than inclusively.

As used herein the term “about” means a variability of 10% from the reference given, unless otherwise specified.

Methylphenidate/Dexmethylphenidate-Ion Exchange Resin Complex

A selected MPH can be complexed with, or loaded onto, a cation exchange resin, using methods which are known in the art. See, e.g., WO 2007/109104, and the documents cited therein. Cationic exchange resins are readily selected for use as described herein.

A number of the processing steps described herein, including, e.g., loading, pre-washing, complexing and granulation may be carried out in a multi-purpose apparatus, e.g., such as the PEF 450 processor [Pall SeitzSchenk] or another similar and larger scale multi-purpose apparatus which is available commercially [e.g., by Rosenmund, U.S. Pat. No. 5,609,835]. The vessel is capable of or adapted for pivoting and has a single chamber with the capacity for handling a reaction/crystallization, filtration, resuspension, and drying. Such a vessel is typically provided with a water jacket connected with a thermostatically controlled heating and cooling system. Alternatively, the processing steps described herein may be carried out in another type of apparatus, or other multiple different apparatus, such as are known in the art.

Ion Exchange Resins

Cationic exchange resins vary in strength, i.e., in their ability to exchange cations. In one embodiment, a relatively strong cationic resin, e.g., Amberlite® IRP69, manufactured by Rohm and Haas (a sulfonated copolymer of styrene and divinylbenzene) is selected. Alternatively, one may select a relatively weak cationic exchange resin, e.g., Amberlite® IRP88 [Rohm and Haas, a crosslinked polymer of methacrylic acid and divinylbenzene)], a weakly acidic (potassium ion) cation exchange resin with 4% cross-linked methacrylate (100 to 500 mesh, equivalent to about 150 microns to about 27 microns, ASTM standard) or Amberlite® 64 (a methacrylic acid and divinylbenzene polymer (hydrogen ion) polyacrilex resin, Rohm and Haas, with a particle size ranging from 100 to 400 mesh (equiv to 35 microns to 150 microns, ASTM standard size), capacity ˜10 meq/g by dry weight). Further, either regularly or irregularly shaped particles may be used as cation exchange resins according to the present invention. Regularly shaped particles are those particles that substantially conform to geometric shapes such as spherical, elliptical, cylindrical and the like, which are exemplified by Dowex® 50WX8 (The Dow Chemical Company). Irregularly shaped particles are all particles not considered to be regularly shaped, such as particles with amorphous shapes and particles with increased surface areas due to surface channels or distortions. Irregularly shaped ion-exchange resins of this type are exemplified by Amberlite® IRP-69 (manufactured by Rohm & Haas), the use of which is illustrated in the examples below. This cation exchange resin is a sulfonated polymer composed of polystyrene cross-linked with about 8% of divinylbenzene, with an ion-exchange capacity of about 4.5 to 5.5 meq/g of dry resin (H⁺-form). Another cation exchange resin having similar properties is Dowex® 50WX8 (H+ form, linear formula, C₁₀H₁₂.C₁₀H₁₀.C₈H₈)_(x), 200-400 mesh particle size, which is equivalent to about 75 microns to about 35 microns, ASTM standard). Amberlite® IRP-69 consists of irregularly shaped particles with a size range of about 100 to about 500 mesh (about 150 microns to about 27 microns, ASTM standard). Dowex® 50WX8 is more regularly shaped. Resins are generally purchased with a size ranging from about 25 microns to about 400 microns. However, other sizes may be selected, or larger sized particles may be milled to provide smaller particle sizes.

The selected ion-exchange resins may be further treated by the manufacturer or the purchaser to maximize the safety for pharmaceutical use or for improved performance of the compositions Impurities present in the resins may be removed or neutralized by the use of common chelating agents, anti-oxidants, preservatives such as disodium edetate, sodium bisulfite, sodium metabisulfite, and so on by incorporating them at any stage of preparation either before complexation or during complexation or thereafter. These impurities along with their chelating agent to which they become bound may be removed before further use of the ion exchange resin.

The amount of methylphenidate that can be complexed with a resin will typically range from about 5% to about 50% by weight of the MPH-ion exchange resin complex particles. A skilled artisan with limited experimentation can determine the optimum loading for any MPH-ion exchange resin complex. In one embodiment, loading of about 10% to about 40% by weight, more desirably, about 15% to about 30% by weight, or about 25% of the MPH-ion exchange resin complex particles can be employed. In one embodiment, a composition of the invention contains MPH complexed to a sodium polystyrene sulfonate resin in at a ratio of 20 MPH (based on the weight of the MPH salt) to 300 resin to 80 MPH (based on the weight of the MPH salt) to 100 resin. In another embodiment, the MPH (based on the weight of the MPH salt) to resin ratio is 4:10 to 1:10, or about 4:10 to about 2:10. In a further embodiment, the dexMPH permits the use of about half the amount of active required when racemic MPH is the active drug.

In one embodiment, following complexation, a MPH-ion exchange resin complex may be, in no particular order, milled to achieve a desired size range and dried (e.g., to a moisture content below about 10%, e.g., about 3% to about 7%), and then stored for future use. In one embodiment, the complex is milled or passed through a sieve to provide a particle size ranging from about 40 microns to about 410 microns to enhance mouth feel (i.e., texture), or about 50 microns to about 250 microns. These particles may be either regularly or irregularly shaped. In some embodiments, the average particle size of the uncoated MPH-ion exchange resin complex or the average particle size of the coated MPH ion exchange resin complex is milled to a size of about 100 to about 200 microns. These particle sizes may be determined using sieve analysis through a sieve shaker having USP standard wire mesh sieves conforming to ASTM specifications.

In one embodiment, a matrix forming polymer is combined with the MPH-ion exchange resin complex following only partial complexation, or by reducing the moisture content of the wet MPH-ion exchange resin complex to a range of between about 15 to about 25%, or another suitable amount. Treatment of the MPH-ion exchange resin complex with the matrix forming polymer is as follows.

MPH-Ion Exchange Resin Complex-Matrix

Optionally, a matrix-forming polymer is used to assist in processing an uncoated or precoated MPH-ion exchange resin complex. For example, a matrix-forming polymer may be used to facilitate granulation of the immediate release MPH component (e.g., an uncoated MPH-ion exchange resin complex). Alternatively, the matrix-forming polymer may be used for another purpose.

In one embodiment, a polyvinylpyrrolidone polymer [e.g., such as may be purchased commercially as Kollidon® 30] is combined with the methylphenidate-ion exchange resin complex in order to facilitate granulation prior to coating. Other hydrophilic polymeric granulating agents may include water-soluble polymeric materials which have been described in the art as impregnating agents or solvating agents and which function in the present application as granulating agents. In one embodiment, the granulating agent is a polyethylene glycol. Examples of desirable impregnating/solvating agents include those described in U.S. patent application Ser. No. 11/724,966, filed Mar. 15, 2007, Published as US 2007-0215511A, Sep. 20, 2007, and Meadows, U S 2003-0099711, which are incorporated herein by reference, or in U.S. Pat. No. 4,221,778 and published US Patent Application Publication No. US 2003/0099711 A1, the disclosures of which are incorporated herein by reference. Specific examples of other impregnating agents include propylene glycol, polyethylene glycol, polyvinyl alcohol, hydroxypropyl methylcellulose, hydroxypropyl cellulose, and sorbitol.

Optionally, the MPH release rate from the compositions of the present invention may be admixed or granulated with a water-soluble or water-insoluble polymer or a combination of a water-insoluble polymers prior to the application of the water-permeable diffusion barrier coating described herein. Upon admixture, these polymers do not form a separate layer on the MPH-ion exchange resin complex, but form a matrix therewith. Examples of suitable matrix forming polymers include, for example, a polyvinyl acetate polymer or a mixture of polymers containing same (e.g., KOLLICOAT® SR 30D), cellulose acetates, ethylcellulose polymers (e.g., AQUACOAT™ ECD-30 or SURELEASE™), acrylic based polymers or copolymers (e.g., represented by the EUDRAGIT family of acrylic resins), cellulose phthalate, or any combination of such water-insoluble polymers or polymer systems. These matrix-forming polymers when used may further prolong or alter the release of the MPH from the ion exchange resin complex/matrix and maximize attaining the desired release profile. One suitable polymer is a polyvinyl acetate polymer as described herein or an acrylic polymer from the EUDRAGIT family. Examples of suitable acrylic polymers from the EUDRAGIT family may include, e.g., a copolymer comprising ethyl acrylate and methyl methacrylate (e.g., EUDRAGIT® NE-30D), or EUDRAGIT® RS30D, RL30D, which are largely pH-independent polymers. EUDRAGIT® RS30D is a 30% aqueous dispersion of poly (ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride) in a ratio of 1:2:0.1; other aqueous dispersions of this copolymer may be selected. Eudragit® RL30 D is a 30% aqueous dispersion of poly (ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.2; other aqueous dispersions of this copolymer may be selected for use in the invention. Although less desirable, certain pH-dependent (enteric) polymers including, e.g., members of the EUDRAGIT polymer family, e.g., the L, S, and E, polymers and others which are commercially available may be selected.

The quantity of polymer that is added to an uncoated or precoated MPH-ion exchange resin complex as a matrix forming polymer typically ranges from about 1% to about 30%, or about 3 to about 20%, or about 3 to about 10%, about 10% to about 15%, about 15 to 25%, or about 1 to about 5% or more by weight of the uncoated or precoated MPH-ion exchange resin particulates prior to their being coated. However, higher or lower amounts may be selected. In one embodiment, where it is desired for the matrix forming polymer to have little or no effect on release rate, a hydrophilic polymer may be selected and used in a higher amount, whereas a hydrophobic release retardant if selected for use will be used at a lower amount. Following admixing, the uncoated or precoated MPH-ion exchange resin complex particles with the matrix forming polymer, the mixture is dried and the MPH-ion exchange resin complex-matrix granules are milled appropriately to the desired particulate size.

For the precoated MPH-ion exchange resin complex-matrix which will be coated and the uncoated MPH-ion exchange resin complex, the particles are milled though a size below about 410 microns, or generally in the range of about 50 microns to about 410 microns, or about 100 microns to about 410 microns. This can be achieved, e.g., using a CO-MIL device fitted with a 40 mesh screen. In one embodiment, the particles have an average size of about 100 to about 250 microns, or about 100 to about 200 microns. In some cases, the milling may be carried out before the complete drying of the complex or complex matrix and then again further drying followed by milling to obtain the desired complex characteristics. These particle sizes may be determined using sieve analysis through a sieve shaker having USP standard wire mesh sieves conforming to ASTM specifications.

Barrier Coat for Sustained Release

The sustained release component of a MPH chewable tablet of the invention contains a methylphenidate-ion exchange resin complex-matrix with a barrier coating which modifies the release profile of the methylphenidate-ion exchange resin complex-matrix such that the methylphenidate has about a 12 hour sustained release profile. Suitably, the barrier coating has a pH-independent release (i.e., it is not an enteric coating which has pH-dependent release) and is a water-insoluble, water-permeable coating material. In a preferred embodiment, neither the chewable tablet nor any of its components has an enteric coating.

Suitably the properties of the barrier coating provide sustained release properties to the barrier coated MPH-ion exchange resin complex, which is MPH-ion exchange resin is optionally in matrix. When the matrix is present, the barrier coating is applied over the MPH-ion exchange resin complex-matrix. The barrier coating provides the sustained release component with resistance to grinding forces which enables the portions of a chewable tablet of the invention to provide a sustained release MPH profile even when cut into pieces.

The barrier coating has a characteristic high flexibility or elongation (elasticity) at break measured by the texture analyzer TA-XT2 HiR (Stable Microsystems) and by the method reported by the manufacturer in its literature [i.e., Jan-Peter Mittwollen, Evaluation of the Mechanical Behavior of Different Sustained Release Polymers, Business Briefing: Pharmagenerics, 2003, pp. 1-3, BASF], with a tensile strength in a range of at least about 150% to about 400%. When the polyvinylacetate based barrier coating described herein is selected, this is achieved while not substantially increasing the tackiness of the polymer film greater than about 2 (wherein the film is measured by the Hossel method referenced above independent of any composition on which it has been deposited).

In one embodiment, the barrier coating layer is about 10% to about 70%, by weight, or about 15% to about 65%, by weight, of the precoated methylphenidate-ion exchange resin complex-optional matrix in order to provide the sustained release component. In another embodiment, the barrier coating layer is about 20% to about 50%, about 25% to about 40% by weight, about 25% to about 35% by weight, or about 30%, by weight of the precoated methylphenidate-ion exchange resin complex-optional matrix (i.e., prior to coating). Still other suitable ranges can be determined by one of skill in the art, having been provided with the information herein.

The barrier coating is applied over the uncoated or precoated MPH-ion exchange complex-optional matrix (e.g., as an aqueous dispersion or a solution), dried, and milled or passed through a screen such that the barrier coated MPH-ion exchange complex-optional matrix particles are in the same size range as described in the preceding paragraph, i.e., in the range of about 50 to about 410 microns.

In one embodiment, the barrier coating is applied as an aqueous dispersion which is dried in order to provide the desired sustained release profile. In the case of an aqueous-based polyvinylacetate coating, the coating is cured in order to provide the desired release profile.

In one embodiment, the barrier coating is applied as an aqueous dispersion of a water insoluble polymer comprising a polyvinyl acetate polymer, or a blend of polymers comprising a polyvinyl acetate polymer. In one embodiment, the barrier coating further contains a plasticizer, which can facilitate uniform coating of the MPH-ion exchange resin complex and enhances the tensile strength of the barrier coating layer.

One coating composition useful in the present invention is applied in the form of an aqueous dispersion containing polyvinylacetate (PVA) polymer based aqueous coating dispersion and a plasticizer. The PVA is insoluble in water at room temperature. The PVA may be used in either substantially pure form or as a blend. Where the barrier coating comprises a PVA polymer, the PVA polymer is present in an amount of about 70% to about 90% w/w of the final barrier coating layer, at least about 75%, at least about 80%, about 85% w/w of the final barrier coating layer. Generally, a plasticizer is used in the percent range, or a mixture of plasticizers combine to total about 2 to about 50% by weight of the coating layer, more preferably about 2.5% to about 20% by weight of the coating layer on the coated MPH-ion exchange resin complex. Preferably a plasticizer is in a range of about 2.5 to about 15% by weight of the coating layer based on the coated complex provides the most desirable properties. Suitable plasticizers may be water soluble and water insoluble. Examples of suitable plasticizers include, e.g., dibutyl sebacate, propylene glycol, polyethylene glycol, polyvinyl alcohol, triethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, tributyl citrate, triacetin, and Soluphor® P (2-pyrrolidone), and mixtures thereof. Other plasticizers are described in US Patent Application Publication US 2003/0099711 A1, May 29, 2003, page 4 (0041) the disclosure of which is incorporated herein by reference.

A commercial polyvinylacetate blend contains primarily a polyvinylacetate polymer, a stabilizer, and minor amounts of a surfactant such as sodium lauryl sulfate. Where the barrier coating comprises PVP as the stabilizer component, the final barrier coating layer generally contains about 5 to about 10% w/w of polyvinyl pyrrolidone. In one desired embodiment, the aqueous based barrier coating solution is KOLLICOAT® SR 30 D (BASF Corporation) and whose composition is about 27% PVA polymer, about 2.7% polyvinylpyrrolidone (PVP), about 0.3% sodium lauryl sulfate (solids content 30% w/w), mixed with a plasticizer. See, also, U.S. Pat. No. 6,066,334 and U.S. Pat. No. 6,026,277, which is incorporated by reference herein. The PVP and surfactant help stabilize the aqueous dispersion of the PVA. Generally, such stabilizing components are present in an amount totaling less than about 10% w/w, and preferably less than about 5% w/w. Optionally, a selected surfactant is present in an amount of about 1% or less. In one embodiment, the surfactant is a non-ionic surfactant. Optionally, an ionic surfactant may be selected.

In a particularly desirable embodiment, the desired modified release is obtained when the coating layer formed by application of the aqueous dispersion containing the KOLLICOAT® SR-30D-plasticizer is dried and cured. Preferably, the coating is cured for about 1 to about 24 hours. In alternate embodiments, the coating is cured for about 4 to about 16 hours, and preferably about 5 hours at high temperature, e.g., about 50° C. to about 65° C., and preferably about 60° C. Thus, in one embodiment, the coated MPH-cation exchange resin complex-matrix has a cured water-permeable, high tensile strength, water insoluble, barrier coating comprising a non-ionic polymer and a plasticizer and having an elongation factor in the range of about 150% to 400% over the MPH-cation exchange resin complex-matrix. In one embodiment, the barrier coating comprises a polyvinylacetate polymer, a stabilizer, a surfactant and a plasticizer. In one embodiment, a barrier coating comprises about 2.5 to about 15% of plasticizer, about 70 to about 90% polyvinylacetate, about 5 to about 10% polyvinylpyrrolidone, and about 0.1 to about 1% surfactant. See, e.g., Mehta et al, US Published Patent Application No. US 2007-0215511A, published Sep. 20, 2007, and its counterpart application, WO 2007/109104, which are incorporated herein by reference.

It may be possible to select other aqueous or non-aqueous solvent based systems which do not require curing. For example, an aqueous based acrylic polymer (a Eudragit® RL30D and Eudragit® RS30D blend is described herein), but requires the addition of anti-tacking agent such as, e.g., talc or glycerol monostearate (GMS), in order to facilitate processing and even coating.

In one embodiment, the coating may be a EUDRAGIT® brand acrylate based coating materials [including, e.g., a poly (ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride) polymer system]. For example, Eudragit® RS 30D [a pH-independent, 30% aqueous dispersion of poly (ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.1)], or Eudragit® RL 30D [a 30% aqueous dispersion, pH independent polymer, poly (ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride) 1:2:0.2)] may be selected as the barrier coating. In one embodiment, a blend of Eudragit® RS 30D and Eudragit® RL 30D may be prepared to optimize the hydrophilicity/hydrophobicity of the film in order to achieve desirable release profiles. Suitably, a plasticizer may be included in the coating composition. In one embodiment, the barrier coating comprises about 2.5 to about 15% of plasticizer. Individual or a combination of hydrophilic or lipophilic plasticizers with a dispersion or suspension containing the barrier coating polymer. Such plasticizers include, e.g., propylene glycol, polyethylene glycol, triacetin, triethyl citrate, dibutyl sebacate, vegetable oil, lipids, etc. Optionally, a suitable anti-tacking agent may be mixed with one of the Eudragit™ products to improve flow during coating and to address issues of tackiness of the product during processing. Suitable anti-tacking agents include, e.g., talc, glycerol monostearate (GMS), and mixtures thereof. Suitably, these agents are present in an amount of about 0.2%-4.5% w/w based on the dry weight of the coating polymer applied to form the coating layer of the sustained release component. Typically, the coating layer resulting from application of the blend described in this paragraph is not subject to any curing.

Optionally, another barrier coating may be selected. In another embodiment, non-aqueous solvent-based ethylcellulose such as in commercially available as the line of ETHOCEL™ products by Dow] may be modified in order to achieve the barrier coating characteristics defined herein, e.g., by addition of a sufficient amount of plasticizer to improve flexibility and/or by curing to a sufficient temperature to achieve the desired release rate. Dow's web site describes three of these products, Std 7 (viscosity of 6-8 mPa-s (CP); Std 10 (9-11 mPa-s (CP); Std 20 (18-22 mPa-S), each of which has a 48.0-49.5% ethoxyl content) as being useful for tablet coating. Further, optionally combining one of these polymers in combination with a water-soluble active and/or water-soluble excipient such as a METHOCEL™ cellulose ether and/or CARBOWAX™ polyethylene glycols is further described. Alternatively, it may be possible to modify an aqueous based ethylcellulose barrier coating in order to achieve the extended release barrier coating characteristics required herein, e.g., by addition of a sufficient amount of plasticizer to improve flexibility and/or by curing to a sufficient temperature to achieve the desired release rate. See, e.g., the barrier coatings described in Kolter et al, U.S. Pat. No. 6,066,334 and U.S. Pat. No. 6,046,277 and See, also, e.g., Wen, U.S. Pat. Nos. 6,046,277 and 6,001,392; Meadows, US Published Patent Application No. 2003/0099711 and related application WO 03/020242; Sovereign Pharmaceuticals, WO 2006/022996 and related applications US Published Patent Application Nos. US2005/0232986; US2005/0232987; US2005/0232993; US2005/0266032; Bess, et al, U.S. Pat. No. 7,067,116; Goede et al, U.S. Pat. No. 6,667,058, Wen et al, U.S. Pat. No. 6,001,392, among others.

A coating as described herein may be applied using techniques described by the polymer manufacturer and/or techniques which are known to those of skill in the art. Suitable methods and apparatus have been described in the patent and non-patent literature and include, e.g., spraying in a fluid bed processor. The coating solution can be sprayed in a fluid bed processor (e.g., VECTOR™ FLM-1 fluid bed processor) using Wurster process. The Coated MPH Resin Complex is then dried and/or cured. The dried, optionally cured, coated methylphenidate-ion exchange resin complex-optional matrix may be passed through a suitable screen in order to ensure that the particle size is in the desired range, e.g., capable of passing through a standard 40 mesh screen. In one embodiment, the dried, optionally cured, coated MPH ion exchange resin complex (optional matrix) granules have a mean particle size in the range of about 100 microns to about 450 microns, or about 150 to about 300 microns.

Finished Dose Formulations

The invention provides MPH extended release chewable tablets. In order to prepare the finished dose form, the three MPH components are blended with excipients and compressed into a chewable tablet. In one embodiment, the excipients do not provide the extended release properties of the chewable tablet. The sustained release profile is provided by the sustained release barrier coated MPH-ion exchange resin complex-matrix component.

The three MPH components may be pre-blended in the desired ratio to one another prior to being admixed with the excipients, described below. Alternatively, each of the three MPH components are added separately and blended with the excipients.

As described above in this specification, the sustained release barrier coated MPH-ion exchange resin complex, optionally in a matrix is present in an amount of about 50% w/w to about 90% w/w, about 60% w/w to about 80% w/w, or about 65 w/w to about 75% w/w of the MPH components in the chewable tablet. Thus, the two immediate release components combine to provide about 10% w/w to about 50% w/w, about 20% w/w to about 40% w/w, or about 25% w/w to about 35% w/w of the MPH in the chewable tablet. The uncoated MPH-ion exchange resin complex component is designed to be immediate release as defined herein, and as such, does not contain a coating which functions to slow down release (e.g., no functional amount of an extended release barrier coating or enteric coat). Suitably, the slower onset immediate release MPH-ion exchange resin complex supplies about 5% w/w to about 25% w/w, or about 10% w/w to about 20% w/w, of the MPH in the chewable tablet. The extended release component and the immediate release uncoated MPH-ion exchange resin complex are further in combination with an uncomplexed MPH drug. The faster onset immediate release uncomplexed MPH drug is present in an amount of about 5% w/w to about 30% w/w, or about 10% w/w to about 20% w/w, of the MPH in the chewable tablet. When the two immediate release components are expressed as a ratio, the ratio of MPH in the uncoated MPH-resin complex (optional matrix) to uncomplexed MPH in the chewable tablet is generally in the range of about 6:1 (uncoated MPH-ion exchange resin complex:uncomplexed MPH) to about 1:6 (uncoated MPH-ion exchange resin complex:uncomplexed MPH), or about 2:1 to about 1:2. In one embodiment, the ratio of MPH from the extended release coated MPH-ion exchange resin complex to MPH from the uncoated MPH immediate release component is in the range of about 18:1 (coated MPH:uncoated MPH-ion exchange resin complex (optional matrix)) to about 5:3 (coated:uncoated), or about 8:1 to about 3:1.

In one example of a chewable tablet of the invention, a methylphenidate extended release chewable tablet has a pharmacokinetic profile in which AUC_(0-∞) for methylphenidate has a geometric mean of about 110 ng-hr/mL to about 140 ng-hr/mL, a geometric mean C_(max) of about 10 ng/mL to about 15 ng/mL, T_(max) of about 4 hours to about 5.25 hours and T_(1/2) of about 5 hours to about 7 hours following a single oral administration of an extended release chewable tablet at a dose equivalent to 40 mg racemic MPH HCl in adults.

In another example, the methylphenidate chewable tablet has a pharmacokinetic profile in which AUC_(0-∞) for methylphenidate has a geometric mean of about 113 ng-hr/mL under fasted conditions and about 138 ng-hr/mL under fed conditions, a geometric mean C_(max) of about 12 ng/mL to about 13 ng/mL under fasted and fed conditions, an arithmetic mean T_(max) of about 4 to about 4.5 hours under fasted and fed conditions and an arithmetic mean T_(1/2) of about 5.2 hours under fasted and fed conditions, following a single oral administration of an extended release chewable tablet at a dose equivalent to 40 mg racemic MPH HCl in adults. For example, the extended release chewable tablet may have the pharmacokinetic profile of FIG. 1 following a single oral administration at a dose equivalent to 40 mg racemic MPH HCl in adults.

The MPH extended release chewable tablets may be prepared using one or more of a filler, one or more disintegrant, one or more binder, one or more a buffering agent, one or more lubricant, one or more glidant, or blends of these components. Suitably, the tablets also include taste and/or mouth feel enhancers including, e.g., one or more of a sweetener, a flavorant, a gum, or blends of these components. Optionally, the tablet may also contain a non-functional coating.

As used herein, a “non-functional coating” refers to a coating which contributes no detectable modified release functions. The non-functional coating may be a polymer may serve as a moisture barrier to preserve the integrity of the tablet during storage or to facilitate application of a color coating layer. Additionally or alternatively, the non-functional coating may provide a color coating layer or improve the “smoothness” or mouth feel of the tablet. In one embodiment, the non-functional coating may increase the hardness of the tablet somewhat without affecting the chewability thereof.

Throughout the specification, where weight percentages of excipients and the three active components are provided, the weight percentages are exclusive of any weight added by a non-functional coating. Weight percentages of these non-functional coatings, where present, are provided as weight added, in an amount of about 1% to about 20%, or about 2% to about 10%, or about 3% to about 5% weight added to the finished chewable tablet.

Typically, a chewable tablet will contain a filler or a mixture of fillers in the range of about 10% w/w to about 90% w/w, about 50% w/w to about 85% w/w, or about 50% w/w to about 70% w/w of the total tablet weight. Suitable fillers may include, e.g., Mannitol, Lactose, Maltose, Fructose, Sucrose, Xylitol, Maltitol, Microcrystalline Cellulose, Dicalcium phosphate, Guargum, Xanthan gum, Tragacanth gum, Pre-gelatinized Starch, Compressible sugar, Calcium carbonate, Magnesium carbonate, Calcium sulfate, Dextrates, Maltodextrin. In one embodiment, a chewable tablet of the invention contains a blend of mannitol, xanthan gum, microcrystalline cellulose, and guargum in an amount of about 60% w/w to about 75% w/w. In one embodiment, a gum or a combination of gums is provided in an amount of about 0.25% w/w to about 5% w/w, or about 0.25% to about 1% w/w. In another embodiment, microcrystalline cellulose is provided in an amount of about 5% w/w to about 25% w/w, or about 10% w/w to about 15% w/w based on the total tablet weight prior to any non-functional coating. A product containing a combination of microcrystalline cellulose and guar gum is commercially available as Avicel®, which contains a ratio of 80 parts by weight microcrystalline cellulose to 20 parts by weight guar gum. This blend of microcrystalline cellulose (MCC) and guar gum may be present in an amount of about 5% w/w to about 25% w/w of the total tablet weight.

A chewable tablet as described herein will also contain a disintegrant or blend of disintegrants in the range of about 1% w/w to about 15% w/w, or about 5% w/w to about 10% w/w, or about 7% w/w to about 8% w/w based on the total tablet weight. Suitable disintegrants include, e.g., Crospovidone, Sodium starch glycolate, Croscarmellose sodium, Carboxymethyl cellulose sodium, Carboxymethylcellulose calcium, Starch. In one embodiment, a tablet as described herein contains crospovidone in a range of about 5% w/w to about 10% w/w. or about 7.5% w/w based on the tablet weight prior to any non-functional coating being applied.

The binder for the chewable tablet may be absent (i.e., 0%), or optionally, present in an amount of about 1% w/w to about 15% w/w of the total tablet weight. Examples of suitable binders include polyvinylpyrrolidone (Povidone), Hydroxypropyl methyl cellulose, Hydroxypropyl cellulose, Hydroxyethyl cellulose, Hydroxyethyl cellulose, Methyl cellulose, Polyvinyl alcohol, Starch, Acacia, Alginic acid, Sodium alginate.

In one embodiment, the chewable tablet of the invention contains a sweetener in an amount of about 0.01% w/w to about 3% w/w, or about 0.5% w/w to about 2% w/w, or about 1% w/w to about 2% w/w or about 1.5% w/w, based on the total tablet weight exclusive of any optional non-functional coating. Suitable sweeteners may include, e.g., Aspartame, Saccharin, Saccharin sodium, Sucralose, Sodium cyclamate, Xylitol, Acesulfame Potassium, and blends thereof. Optionally, in addition to functioning as a sweetener, an excipient may function as a filler. Examples of suitable sweeteners/fillers including, e.g., fructose, sucrose, xylitol, maltitol. Optionally, when performing both functions, the excipient may be present in an amount in excess of about 10% w/w of the tablet. In such an instance, additional sweetener may be omitted (e.g., present in 0% added sweetener). Alternatively, a second sweetener or a combination of sweeteners which differs from the filler is added in the amount provided in this paragraph in order to further enhance taste.

Suitably, the tablet is provided with a buffering agent in an amount of about 0.1% w/w to about 5% w/w, or about 0.5% w/w to about 1.5% w/w based on the total tablet weight. Examples of suitable buffering agents include, e.g., citric acid, tartaric acid, malic acid, lactic acid, and acceptable salts thereof, and mixtures thereof. In one embodiment, the buffering agent adjust the pH of the tablet (if suspended in water) to a range of about 3.5 to about 5, or about 4 to about 4.5. In one embodiment, the buffering agent is citric acid, which also provides desirable taste properties.

When an additional flavoring agent is added, the flavoring agent(s) may be added in an amount of about 0.05% w/w to about 3% w/w, or about 0.1% to about 1% w/w or about 0.5% w/w, based on the total weight of the tablet (exclusive of any optional non-functional coating). Suitable flavoring agents may include, both natural and artificial flavoring agents such as are generally available through several custom manufacturers around the world such as Fona [Illinois, US], Givaudan (Vernier, Switzerland), Ungerer & Company (Lincoln Park, N.J.), and International Flavors & Fragrances (New York, N.Y.) to name a few. Those skilled in the art will recognize that there are several commercial sources available including custom blenders. The flavorings may be blended prior to addition to the pharmaceutical composition or added separately. Still other flavoring agents such as cherry, strawberry, vanilla, grape, banana and other flavors or mixtures thereof may be selected.

Optionally, a colorant may be provided to the tablet to provide a desired visual appeal or trade dress. Such colorants may be added in the range of about 0.001 to about 1% w/w, or about 0.01% w/w to about 0.08% w/w or about 0.05% w/w, based on the total weight of the tablet (exclusive of any non-functional coating). Such colorants are available from a variety of sources including, e.g., Colorcon, Noveon, and Spectra.

In order to facilitate production of the chewable tablet, excipients such as lubricants and glidants may be utilized. A lubricant may be utilized in an amount of about 0.1% w/w to about 5% w/w, about 0.2% w/w to about 4.5% w/w, or about 1.5% w/w to about 3% w/w of the total weight of the tablet. Examples of lubricants may include, e.g., Talc, Magnesium Stearate, sodium stearyl fumarate, Stearic acid, Zinc Stearate, Calcium Stearate, Magnesium trisilicate, Polyethylene glycol, and blends thereof. In one embodiment, talc and magnesium stearate are used in tablet preparation. The resulting tablet may contain about 0.1% w/w to about 3% w/w talc and about 0.5% w/w to about 0.5% w/w magnesium stearate. A glidant may be used in an amount of about 0.01% w/w to about 0.5% w/w, or about 0.1% w/w to about 0.3% w/w, based on the total weight of the tablet. Examples of suitable glidants include, e.g., silicon dioxide and tribasic calcium phosphate. In one embodiment, the glidant is silicon dioxide which is used in an amount of about 0.001% w/w to about 0.1% w/w or about 0.05% w/w.

Optionally, other excipients may be selected from conventional pharmaceutically acceptable carriers or excipients and well established techniques. Without being limited thereto, such conventional carriers or excipients include diluents, binders and adhesives (i.e., cellulose derivatives and acrylic derivatives), lubricants (i.e., magnesium or calcium stearate, or vegetable oils, polyethylene glycols, talc, sodium lauryl sulfate, polyoxy ethylene monostearate), thickeners, solubilizers, humectants, disintegrants, colorants, flavorings, stabilizing agents, sweeteners, and miscellaneous materials such as buffers and adsorbents in order to prepare a particular pharmaceutical composition. The stabilizing agents may include preservatives and anti-oxidants, amongst other components which will be readily apparent to one of ordinary skill in the art.

The following Table provides exemplary formulations of MPH extended release chewable tablets according to the invention, based on the total weight of the tablet.

Broad Narrower Component Range w/w Range Coated MPH - ion exchange resin 15%-20% 16%-18% complex (coated MPH polistirex) Uncoated MPH polistirex 1.5%-3.5% 2%-3% Uncomplexed MPH 0.5%-0.9% 0.6%-0.8% Filler(s) 45%-85% 50%-70% Mannitol 40%-60% 45%-55% Xanthan Gum 0.1%-1%  0.25%-0.75% MCC + guar gum  5%-25% 10%-20% Disintegrant(s)  5%-10% 7%-8% Binder(s) 0%-8% 2%-6% Sweetener(s) 0.5%-3%  1%-2% Buffering Agent 0.1%-5%  0.5%-1.5% Flavoring Agent 0.1%-3%  0.1%-1%  Lubricant(s) 0.2%-4.5% 1.5%-3%  Talc 0.1%-3%  1%-2% Magnesium stearate 0.1%-1.5% 0.5%-1%  Glidant 0.01%-1%   0.1%-0.3% Colorant 0.01%-0.5%  0.02%-0.08%

Suitably, a chewable tablet of the invention is prepared as a single uniform solid dispersion. A typical manufacturing process for making a chewable tablet generally involves blending of the desired ingredients to form a uniform distribution of the coated MPH-ion exchange resin complex, the uncoated MPH-ion exchange complex, the uncomplexed MPH, and the excipients. If desired, a blend of the three MPH components may be formed prior to blending into the excipient. The blend is then compressed into a single layer using standard methods and tablet presses such as well-known to those skilled in the art (e.g., Kilian, Fette, Kirsch, Elizabeth, Sejong, Kikisui, SMI, Colton, Stok, and Manesty, amongst others.)

The working examples below describe forming a chewable tablet of the invention into a capsule shape, optionally with a single bisect (a single scoring at the mid-line which facilitates splitting the tablet into halves). However, other shapes may be readily selected, including, e.g., a standard round shape, a flat faced shape, oval, bullet, square, triangle, diamond, pentagon, octagon, amongst others. Optionally, one or more of these tablet shapes may be provided with a quadrisect, i.e., two perpendicular scores which facilitate splitting the tablet into quarters.

Optionally, the tablet may have one or more sealant or top coating which does not function to modify or extend release but which provides moisture barrier, of a color coating or other visual appeal. For example, such a coating may provide a “shine” to the tablet, enhance palatability, serve as an identifying color for the tablet, or other purposes. Such coatings are available commercially, e.g., from Colorcon or other suppliers. Typically, such a coating is composed of hydroxypropylmethylcellulose (HPMC) or polyvinylalcohol and is present in an amount of about 1% w/w to about 20% w/w, or about 2% w/w to about 10% w/w of the total tablet weight.

The finished tablets may be stored in glass or high density polyethylene (HDPE) bottles with or without a heat induced sealed (HIS) bottle. The bottle may also contain a dessicant. Alternatively, the tablets may be encapsulated into blister packs using standard methods well-known to those skilled in the art.

An MPH extended release chewable tablet of the invention may be orally administered to a patient having a disorder treatable by MPH. These include disorders for which regulatory approval has been granted in the US or other jurisdiction in which the drug is being administered and which requires regulatory approval. For example, MPH is currently approved for treatment of Attention Deficit Hyperactivity Disorder (ADHD), postural orthostatic tachycardia syndrome, and narcolepsy. MPH has also been described in patent applications and in the literature as being useful for treatment of such disorders including, but are not limited to, behavioral disorders, treatment-resistant cases of lethargy, depression, neural insult, obesity, and rarely other psychiatric disorders such as obsessive-compulsive disorder, Attention Deficit Disorder, specific dyslexias, brain dysfunction, cognitive decline in AIDS and AIDS related conditions, alertness in geriatric, Alzheimer's patients and recovering stroke victims.

Thus, the invention provides a method of treating one or more of the above disorders for a period of at least twelve hours by administering a MPH extended release chewable tablet containing a blend of a barrier coated methylphenidate-ion exchange resin complex-matrix, a first MPH immediate release component (e.g., an uncoated MPH-ion exchange resin complex), and a second MPH immediate release component (uncomplexed MPH).

A composition of the invention is formulated to deliver MPH is, most desirably, in dosages ranging from about 1 mg up to about 100 mg per day, preferably from about 10 to about 75 mg per day, or in about 25 or 60 mg doses [based on equivalence to racemic methylphenidate HCl] although variations will necessarily occur depending upon the weight and condition of the subject being treated and the particular route of administration chosen. Actual dosages of dexmethylphenidate may be at half the amounts of racemic methylphenidate. Variations may nevertheless occur depending upon the weight and condition of the persons being treated and their individual responses to said medicament.

As described herein, the MPH extended release chewable tablets of the invention can be dosed orally twice-a-day at 12-hour intervals. However, depending upon the patient, smaller doses may be delivered at intervals during the day. Other patients may take a single dose in the morning and forego dosage in the evening.

An in vitro dissolution test determines whether chewable tablets disintegrate within a prescribed time when placed in a dissolution media under prescribed experimental conditions. Disintegration is defined as the state in which no residue of the tablet, except fragments of undissolved coating, remains on the screen of the test apparatus or, if any other residue remains, it consists of a soft mass having no palpably firm, unmoistened core.

Suitable methods for in vitro testing of chewable tablet dissolution have been described, e.g., by the World Health Organization (WHO) International Pharmacopoeia, (http://www.who.int/medicines/publications/pharmacopoeia/). An example of a suitable disintegration apparatus is described as follows. The apparatus consists of a circular basket-rack assembly, a suitable vessel for the immersion fluid (such as a 1-liter beaker), a thermostatic arrangement for maintaining the fluid at the required temperature (normally 37±2° C.), and a device for raising and lowering the basket-rack in the immersion fluid at a constant frequency of 28-32 cycles/min through a distance of 50-60 mm. The basket-rack assembly consists of six open-ended cylindrical glass tubes and a rack for holding them in a vertical position. The tubes are 75-80 mm long, and have an inside diameter of about 21.5 mm and a wall about 2 mm thick. The tubes are held vertically by two superimposed plates, circular in shape and made of transparent plastic material, each about 90 mm in diameter and 6 mm thick, perforated by six holes of a diameter that allows the tubes to be inserted. The holes are equidistant from the center of the plate and equally spaced one from another. A piece of woven gauze, made of stainless steel wire about 0.635 mm in diameter, with a mesh aperture of 2.0 mm is attached to the underside of the lower plate. The upper plastic plate is covered with a stainless steel plate, about 1 mm thick, of a diameter similar to that of the plastic plates. The steel plate is perforated by six holes about 22 mm in diameter, positioned to coincide with those of the upper plastic plate. It is placed over the tubes and consolidates the whole structure. The plates are held rigidly 75-80 mm apart by vertical stainless steel rods at the periphery. A metal rod is fixed to the center of the upper plate. This enables the assembly to be attached to a suitable mechanical device so that it may be lowered and raised. The volume of the fluid in the immersion vessel should be such that, at the highest point of the upward stroke, the wire mesh that forms the bottom of the basket remains at least 25 mm below the surface of the fluid. At the lowest point of the downward stroke, it should descend to not less than 25 mm from the bottom of the vessel. The time required for the upward stroke should be equal to the time required for the downward stroke, and the change in stroke direction should be a smooth transition rather than an abrupt reversal of motion. Where a disc is prescribed in the monograph, the following configuration and dimensions apply: a cylindrical disc 20.7±0.15 mm in diameter and 9.5±0.15 mm thick, made of transparent plastic with a relative density of 1.18 to 1.20. Each disc is pierced by five holes 2 mm in diameter, one in the center and the other four spaced equally on a circle of radius 6 mm from the center of the disc. On the lateral surface of the disc, four equally spaced grooves are cut so that on the upper surface of the disc they are 9.5 mm wide and 2.55 mm deep and, at the lower surface, 1.6 mm square. Different designs of basket-rack assembly may be used, provided that the specifications for the glass tubes and the stainless steel wire gauze are maintained. In vitro dissolution of the methylphenidate chewable tablet of the invention may be assessed through a variety of methods including, e.g., Food and Drug Administration (FDA)-accepted dissolution tests, including the Basket Method (I) approved for use with a methylphenidate chewable tablet, http://www.accessdata.fda.gov/scripts/cder/dissolution/dsp_SearchResults_Dissolutions.cfm, have been described. The current FDA-approved dissolution test for a prior art methylphenidate chewable tablet utilizes water and a paddle speed of 100 rpm, at 900 mL, with testing at 15, 30, 45 and 60 minutes. Other methylphenidate tablets have different dissolution tests and different media. However, since the barrier coated methylphenidate-ion exchange complex described herein is not readily soluble in water, the previously described tests are dissolution medium is not suitable for testing dissolution of the present tablets at those time frames. Accordingly, a dissolution medium of phosphate buffer is utilized in the working examples below to assess in vitro dissolution of the MPH extended release chewable tablets described herein of the invention rather than water.

Suitably, the MPH extended release tablet of the invention can be scored without affecting the extended release profile. Thus, the oral dose is readily titrated, i.e., split in half, in order to readily and accurately deliver half the dose of the finished tablet.

EXAMPLES

The following examples are illustrative only and are not intended to be a limitation on the present invention.

Example 1: Methylphenidate (MPH) Extended Release (ER) Chewable Tablets (CT) Prepared Using a Blend of Eudragit® RS 30D and Eudragit® RL 30D Polymer as Barrier Coating for Sustained Release Component

In the below example the Finished product, MPH ERCT—20 mg contains 70% of the dose as Coated (Eudragit® RS 30D and Eudragit® RL 30D) MPH Polistirex Matrix, 15% of dose as Uncoated MPH Polistirex and 15% of the dose as MPH HCl.

A. Coated Methylphenidate Polistirex

Ingredients Quantity Uncoated Methylphenidate - Ion exchange resin complex (Uncoated MPH Polistirex) Methylphenidate (MPH) HCl (Covidien) 3100 g Sodium Polystyrene Sulfonate Amberlite ® 7693 g IRP69 ion exchange resin [Rohm Haas] Purified Water* Qs* Pre-Coated MPH Polistirex Uncoated MPH Polistirex 8500 g Povidone [Kollidon ® K30, BASF] 657 g Purified water* 2629 g Purified Water* Qs* Coated MPH Polistirex Pre-coated MPH Polistirex - (Povidone) 600 g Matrix Poly(ethyl acrylate-co-methyl methacrylate- 75.26 g co-trimethylammonioethyl methacrylate chloride) 1:2:0.2 [Eudragit ® RL30D dispersion**, Evonik] Poly(ethyl acrylate-co-methyl methacrylate- 376.3 g co-trimethylammonioethyl methacrylate chloride) 1:2:0.1 [Eudragit ® RS30D dispersion**, Evonik] Triethyl Citrate 27.0 g Talc 33.87 g Purified Water* 694.56 g *Removed during processing **30% w/w aqueous dispersion

1. Uncoated Methylphenidate Polistirex

The MPH-ion exchange resin complex (MPH polistirex), was prepared by first adding 80 L of Purified Water into a PEF 450 PallSchenk vessel and dissolving methylphenidate HCl by continuous mixing. Sodium Polystyrene Sulfonate ion exchange resin [Amberlite® IRP69, Rohm & Haas] was dispersed with continuous mixing and the mixing was continued for 60 minutes. Water was removed by filtration process followed by rinsing twice using purified water (40 L). Wet resin complex was then dried until moisture content was between 3-7%. Dried MPH-ion exchange resin complex was passed through a 40 mesh screen using the CO-MIL® device. This was the Uncoated MPH Polistirex.

In a separate container Povidone (polyvinylpyrrolidone) was dissolved in 2629 gms of Purified Water (Povidone solution). Uncoated MPH Polistirex prepared as described earlier in this example was treated with Povidone solution with continuous mixing to form a uniform mass of uncoated MPH polistirex in a matrix with the povidone. The uncoated MPH polistirex-matrix was dried until the moisture content was between 15-25%. Semi-dried MPH polistirex-matrix was then milled using CO-MIL® brand mill fitted with 40 mesh screen. Milled MPH polistirex-matrix was further dried until moisture content was between 3-7%. Dried MPH polistirex-matrix was passed through a CO-MIL® fitted with 40 mesh screen. This was the Pre-Coated MPH Polistirex-Matrix.

The Coated MPH Polistirex-Matrix was prepared as follows.

The coating solution was prepared by mixing Purified water and Triethyl Citrate in a container and later Talc was dispersed using high shear mixer for 10 minutes (Talc dispersion). In a separate container Eudragit® RS 30D and Eudragit® RL 30D were added and mixed with Talc dispersion for 45 minutes. The coating process was performed in a fluid bed processor equipped with Wurster column by applying coating solution on to Pre-coated MPH Polistirex-Matrix that resulted in 30% weight gain. The Coated MPH Polistirex-Matrix was again passed through Sieve No. 40 mesh screen.

B. Methylphenidate ER Chewable Tablets

Ingredients qty/batch (g) Coated MPH Polistirex - (Povidone) 60.45 Matrix from Part A Uncoated MPH Polistirex from Part A 8.01 MPH HCl 2.25 Mannitol 145.44 Xanthan gum 1.5 Crospovidone 22.5 Microcrystalline Cellulose and Guar 45 gum [Avicel ® FMC Biopolymer, 80:20 weight ratio of MCC to guar gum] Aspartame 4.5 Citric acid 3 Flavor 1.5 Talc 3 Silicon dioxide 0.6 Magnesium stearate 2.25

Mannitol and Microcrystalline Cellulose and Guargum were screened through 20 mesh screen and loaded into the cube blender. Coated MPH Polistirex-Matrix prepared as in the previous section, Uncoated MPH Polistirex, MPH HCl, Xanthan gum, Crospovidone, Aspartame, Citric acid, Flavor, Talc, Silicon dioxide were screened through 40 mesh screen and loaded into the cube blender and mixed for 10 minutes. Magnesium Stearate was screened through 40 mesh screen and loaded into the blender and mixed for additional 5 minutes. The powder blend was compressed on a 10 station rotary tablet press using 0.2625×0.5720 capsule shaped tooling. The final weight of the compressed tablet was 400 mg.

Example 2: Methylphenidate ER Chewable Tablets Prepared Using a Cured Polyvinylacetate-Plasticizer Barrier Coating for Sustained Release Component

In the below example the Finished product, MPH ERCT—40 mg contains 70% of the dose as Coated (Kollicoat SR 30D) MPH Polistirex-Matrix, 15% of dose as Uncoated MPH Polistirex and 15% of the dose as MPH HCl.

A. Coated Methylphenidate Polistirex

Ingredients Quantity Uncoated Methylphenidate Polistirex MPH HCl 15500 g Sodium Polystyrene Sulfonate Amberlite ® 38450 g IRP69 ion exchange resin Purified Water* Qs* Pre-Coated MPH Polistirex Uncoated MPH Polistirex 40000 g Povidone (Kollidon ® K30; BASF) 3092 g Purified water* 12372 g Purified Water* Qs* Coated MPH Polistirex Pre-coated MPH Polistirex - (Povidone) 34000 g Matrix Polyvinyl Acetate Dispersion** 34300 g (Kollicoat ® SR30D, BASF) Triacetin 513 g Purified Water* 19200 g *Removed during processing **30% w/w aqueous dispersion

The MPH-ion exchange resin complex (MPH polistirex) was prepared by first adding 400 L of Purified Water in to a large scale multi-purpose vessel and MPH HCl was dissolved by continuous mixing. Sodium Polystyrene Sulfonate ion exchange resin was dispersed with continuous mixing and the mixing was continued for 60 minutes. Water was removed by filtration process followed by rinsing twice using purified water. Wet MPH polistirex was then dried until the moisture content was between 3-7%. Dried MPH polistirex was passed through a 40 mesh screen using the CO-MIL®. This was the Uncoated MPH Polistirex.

In a separate container Povidone was dissolved in 12372 gms of Purified Water (Povidone solution). Uncoated MPH Polistirex was treated with Povidone solution with continuous mixing to form a uniform mass to provide an uncoated MPH polistirex in a matrix with the povidone. Wet mass was dried until the moisture content was between 15-25%. Semi-dried uncoated MPH polistirex-(povidone) matrix was then milled using CO-MIL® fitted with a 40 mesh screen. Milled material was further dried until moisture content was between 3-7%. Dried uncoated MPH polistirex-(povidone) matrix was passed through a CO-MIL® fitted with 40 mesh screen. This was the Pre-Coated MPH Polistirex-(povidone) matrix.

The Coated MPH Polistirex-Matrix was prepared as follows. The coating solution was prepared by mixing Triacetin, Purified Water and Polyvinyl Acetate dispersion in a separate container. The coating process was performed in a fluid bed processor equipped with Wurster column by applying coating solution on to Pre-coated MPH Polistirex that resulted in 30% weight gain. The Coated MPH Polistirex-Matrix was placed in the hot air oven at 60° C. for 5 hours. The Coated MPH Polistirex-Matrix was again passed through Sieve No. 40 mesh screen. This was the cured, coated MPH Polistirex-Matrix.

B. Methylphenidate ER Chewable Tablets

Ingredients quantity/batch (g) Cured, Coated MPH Polistirex - 16576 Matrix from Example 2 Part A Uncoated MPH Polistirex from 2534 Example 2 Part A MPH HCl 720 Mannitol 48810 Xanthan gum 480 Crospovidone 7200 Microcrystalline Cellulose and 14400 Guar gum [Avicel ® FMC Biopolymer; 80:20 MCC to guar gum ratio by weight] Aspartame 1440 Citric acid 960 Flavor 480 Colorant 48 Talc 1440 Silicon dioxide 192 Magnesium Stearate 720

Mannitol and Microcrystalline Cellulose and Guargum were screened through 20 mesh screen and loaded into the ‘V’ blender. Cured, coated MPH Polistirex-Matrix, Uncoated MPH Polistirex, MPH HCl, Xanthan gum, Crospovidone, Aspartame, Citric acid, Flavor, Talc, Silicon dioxide were screened through 40 mesh screen, Colorant was screened through 60 mesh and loaded into the ‘V’ blender and mixed for 10 minutes. Magnesium Stearate is screened through 40 mesh screen and loaded into the blender and mixed for additional 5 minutes. The resulting powder blend was compressed on a 36 station rotary tablet press using a 0.3310×0.7210 capsule shaped tooling to produce a capsule shaped compressed MPH extended release (ER) chewable tablet. The final weight of the compressed tablet was 800 mg.

C. Non-Functional Coating of MPH ER Chewable Tablet

Ingredients quantity/batch (g) Opadry ® (polyvinylalcohol) 4020 Purified water 36180

In a separate container Opadry® polymer was dispersed in 36180 gm of purified water and mixed for 45 minutes. The coating process was performed in a perforated coating pan by applying coating solution on to the compressed MPH ER Chewable Tablets that resulted in 3% weight gain.

Example 3: Methylphenidate ER Chewable Tablets Prepared Using a Cured Polyvinylacetate-Plasticizer Barrier Coating for Sustained Release Component

In the below example the Finished product, MPH ERCT—40 mg contains 80% of the dose as Coated MPH Polistirex (Kollicoat® SR 30D), 10% of dose as Uncoated MPH Polistirex and 10% of the dose as MPH HCl.

A. Coated Methylphenidate Polistirex

Ingredients Quantity Uncoated MPH Polistirex Methylphenidate HCl 15500 g Sodium Polystyrene Sulfonate Amberlite ® IRP69 ion 38450 g exchange resin [Rohm Haas] Purified Water* Qs* Pre-Coated MPH Polistirex Uncoated MPH Polistirex 30000 g Povidone (Kollidon ® K30) 2319 g Purified water* 10940 g Purified Water* Qs* Coated MPH Polistirex Pre-coated MPH Polistirex - (Povidone) Matrix 32000 g Polyvinyl Acetate Dispersion** (Kollicoat ® SR30D, 32300 g BASF) Triacetin 483 g Purified Water* 18100 g *Removed during processing **30% w/w aqueous dispersion

A MPH-ion exchange resin complex (MPH Polistirex) was prepared by first adding 400 L of Purified Water in to the vessel and dissolving methylphenidate HCl by continuous mixing. Sodium Polystyrene Sulfonate ion exchange resin was dispersed with continuous mixing and the mixing was continued for 60 minutes. Water was removed by filtration process followed by rinsing twice using purified water. Wet MPH polistirex was then dried until moisture content was between 3-7%. Dried MPH polistirex was passed through a 40 mesh screen using the CO-MIL® brand mill. This was the Uncoated MPH Polistirex.

In a separate container Povidone was dissolved in 10940 gms of Purified Water (Povidone solution). Uncoated MPH Polistirex complex was treated with Povidone solution with continuous mixing to form a uniform mass which resulted in the formation of a matrix between the uncoated MPH polistirex and povidone. The wet mass containing the uncoated MPH polistirex-matrix was dried until the moisture content was between 15-25%. Semi-dried uncoated MPH polistirex-matrix was then milled using CO-MIL® brand mill fitted with a 40 mesh screen. Milled uncoated MPH polistirex-matrix was further dried until moisture content was between 3-7%. Dried material was passed through a CO-MIL fitted with 40 mesh screen. This was the Pre-Coated MPH Polistirex-matrix.

The Coated MPH Polistirex-Matrix was prepared as follows. The coating solution was prepared by mixing Triacetin, Purified Water and Polyvinyl Acetate dispersion in a separate container. The coating process was performed in a fluid bed processor equipped with Wurster column by applying coating solution on to Pre-coated MPH Polistirex-Matrix that resulted in 30% weight gain. The Coated MPH Polistirex-Matrix was placed in the hot air oven at 60° C. for 5 hours. The cured, coated MPH Polistirex-Matrix was again passed through number 40 mesh screen. This was the cured, coated MPH Polistirex-Matrix used for preparing the chewable tablet.

B. Methylphenidate ER Chewable Tablets

Ingredients quantity/batch (g) Cured, Coated Methylphenidate Polistirex - Matrix 59.19 prepared according to Example 3 Part A Uncoated Methylphenidate Polistirex prepared 5.34 according to Example 3 Part A Methylphenidate Hydrochloride 1.5 Mannitol 149.97 Xanthan gum 1.5 Crospovidone 22.5 Microcrystalline Cellulose and Guar gum [Avicel ® 45 FMC Biopolymer] Aspartame 4.5 Citric acid 3 Flavor 1.5 Colorant 0.15 Talc 3 Silicon dioxide 0.6 Magnesium Stearate 2.25

Mannitol and Microcrystalline Cellulose and Guargum were screened through 20 mesh screen and loaded into the ‘V’ blender. Coated Methylphenidate Polistirex, Uncoated Methylphenidate Polistirex, Methylphenidate Hydrochloride, Xanthan gum, Crospovidone, Aspartame, Citric acid, Flavor, Talc, Silicon dioxide were screened through 40 mesh screen, Colorant was screened through 60 mesh and loaded into the ‘V’ blender and mixed for 10 minutes. Magnesium Stearate is screened through 40 mesh screen and loaded into the blender and mixed for additional 5 minutes. The powder blend was compressed on a 36 station rotary tablet press using 0.3310×0.7210 capsule shaped tooling. The final weight of the compressed tablet was 800 mg.

C. Non-Functional Coating of MPH ERCT

Ingredients quantity/batch (g) Opadry ® (polyvinylalcohol) 10 Purified water 90

In a separate container Opadry® polyvinylalcohol non-functional coating was dispersed in 90 gm of purified water and mixed for 45 minutes. The coating process was performed in a perforated coating pan by applying coating solution on to the compressed MPH ER Chewable Tablets that resulted in 3% weight gain.

The scored chewable tablet when split, is expected to show the extended release profile as is characteristic of the intact tablet in vitro. The following example shows the in vitro dissolution profiles of split versus whole tablet of the 20 mg and 30 mg methylphenidate ER chewable tablets.

Example 4: Methylphenidate Extended Release Chewable Tablet

A. Split Tablet Dissolution

The tablets used in this study are the same ingredients as described in Example 2 for a 40 mg tablet, with the exception of the non-functional cosmetic coating. In order to prepare the 20 mg tablet used in this study, the same three MPH components and the same excipients as identified in Example 2 were combined at ½ the weight percentages of each ingredient defined in Example 2. In order to prepare the 30 mg tablet used in this study, the same three MPH components and the same excipients as identified in Example 2 were combined at ¾ the weight percentages of each ingredient identified in Example 2.

The following in vitro dissolution assessment was performed using conventional USP testing on the whole (unscored) or split tablets placed in 900 mL 0.4 M potassium phosphate buffer (KH₂PO₄) at 37±0.5° C. with a USP paddle speed of 75 rpm. This assessment was designed to show the in vitro dissolution rate over a twelve hour period.

% Dissolved Form 0.5 h 1 h 2 h 3 h 6 h 8 h 12 h 20 mg, whole tablet 46 55 66 72 84 88 92 20 mg Tablet Split in Half 44 53 65 71 82 85 89 30 mg, whole tablet 46 55 67 74 85 90 94 30 mg Tablet, Split in Half 47 57 69 76 89 93 97

B. Comparative Dissolution Study

In another dissolution study, the 40 mg methylphenidate ER chewable tablet, prepared as described in Example 2, was compared to MPH ER chewable tablets with the sustained release component and only one of the two immediate release components. Thus, 40 mg tablet was prepared with the same excipients in Example 2, but having a combination of the coated MPH polistirex-matrix and only the faster release MPH immediate release component (racemic MPH HCl). The MPH HCl is present in double the weight amount described in Example 2 and the slower release uncoated MPH polistirex is absent. This is the 70/30 coated/MPH HCl tablet shown in the table below. The second comparative 40 mg tablet contains the same excipients as in Example 2, but in contrast to Example 2, the active components are a combination of the coated MPH polistirex-matrix and double the weight amount of the slower release MPH immediate release component (uncoated MPH polistirex); no MPH HCl is included in this formulation. This is the 70/30 coated/uncoated tablet shown in the table below.

Each of the three active components is prepared as described in Example 2. Each of the tablets are prepared as described in Example 2, with the exception of the weights of the immediate release components showing the comparative two-component tablets.

In order to enhance the ability to observe the onset of release within 60 minutes, another study to monitor first hour of dissolution every 10 minutes was used than that described in Example 4A for the split tablet dissolution. With the exception of the buffer strength, the in vitro dissolution assessment was performed as described in Part A above by placing the tablets in 900 mL of the buffer at 37±0.5° C. and using a USP paddle speed of 75 rpm.

% Dissolved 10 20 30 45 60 Form min min min min min 70/30 (coated cured MPH 30 31 32 33 35 polistirex - matrix/MPH HCl) 70/15/15 (coated cured 25 28 30 32 33 MPH polistirex - matrix/ uncoated MPH polistirex/ MPH HCl) Tablet of Example 2 70/30 (coated cured MPH 21 25 27 29 30 polistirex - matrix/ uncoated MPH polistirex)

The initial dissolution profiles show the order of release rate as: coated/MPH HCl>coated/uncoated/MPH HCl>coated/uncoated. The inclusion of MPH HCl to replace a portion of uncoated showed increase in the initial release rate.

C. Compression Pressure Dissolution Study

The chewable tablets when compressed under the pressure of 8 to 23 kp, show no difference in the release profile of the methylphenidate ER chewable tablets. The dissolution study was performed as described in Example 4A. An example of the release rate of the 40 mg formula of Example 2 is listed in the following table. These tested hardness are not limitations on the chewable tablet, but are illustrative only.

Methylphenidate ERCT, 40 mg (70/15/15)—Hardness Study

% Dissolved 0.5 h 1 h 2 h 3 h 6 h 8 h 12 h Comments 47 56 67 74 86 89 92 8-10 kp, Low Hardness 46 55 66 74 86 90 93 14-16 kp, Normal Hardness 47 56 67 75 87 90 93 20-23 kp, High Hardness

Example 5: Single Dose Pharmacokinetics of an Extended Release Methylphenidate Chewable Tablet

A three-way cross-over pharmacokinetic study has been performed using (1) MPH ER chewable tablets prepared according to Example 2 of this specification (Test) dosed 40 mg at 0 hour under fasted condition (2) MPH ER chewable tablets prepared according to Example 2 of this specification (Test) dosed 40 mg under fed condition and (3) IR chewable tablets (reference) [Methylin® 10 mg chewable tablet; Shionogi Inc] dosed 20 mg at 0 and 6 hours under fasted condition.

Calories Total fat Carbohydrate Protein (kcal) (g) (g) (g) 250 mL of whole milk 160 8 12 8 2 slices of bacon 89 7 0 6 Total weight 56 85 36 Total calories (kcal) 504 340 144 Related caloric content 50.6% 34.1% 14.4%

The objective is to determine the relative bioavailability of MPH ER chewable tablets of the invention product versus reference and to also evaluate the food effect on the chewable tablets of the invention.

This is an open-label, single- and multi-dose, randomized, 3-period, 3-sequence, 3-treatment, crossover study, designed to evaluate the relative bioavailability of two formulations of methylphenidate HCl extended release chewable tablets, administered to healthy male and female subjects under fasting and fed conditions. Subjects were randomly assigned to one of the three dosing sequences ABC, BCA, and CAB. Concentrations of total (racemic) methylphenidate were measured from samples collected over a 24-hour interval after dosing in each period. Thirty-three (33) subjects were dosed in Period 1. All 33 subjects are included in the safety dataset. Thirty-two (32) subjects were dosed in Period 2. Thirty (30) subjects were dosed in Period 3. Thirty-one (31) subjects are included in the pharmacokinetic analysis and the statistical analyses. Subjects 10 (ABC) and 18 (CAB) completed only Period 1 of the study. These subjects were not included in the pharmacokinetic dataset. Subjects 29 (ABC) and 33 (ABC) completed Periods 1 and 2, receiving Treatments A and B. Both subjects are included in the pharmacokinetic dataset.

Pharmacokinetics:

The following pharmacokinetic parameters were estimated using a non-compartmental approach: C_(max), AUC_(t), AUC_(inf), AUC0-0.5, AUC0-2, AUC0-3, AUC0-4, T_(max), Kel, and T_(half).

Safety:

An assessment of safety was based primarily on the frequency and severity of AEs. There was no formal evaluation of safety or tolerability.

Statistical Methods:

Descriptive statistics are estimated for the pharmacokinetic parameters in each treatment.

Analysis of variance (ANOVA) was performed on log-transformed C_(max), AUC_(t), AUC_(inf), AUC0-0.5, AUC0-2, AUC0-3, AUC0-4 and on untransformed T_(max), Kel and T_(half) parameters. The significance of the sequence, period, treatment and subject-within-sequence effects was tested.

Using the same statistical model, the least-squares-means, the differences between the treatments least-squares-means and the corresponding standard errors of these differences were estimated for log-transformed C_(max), AUC_(t), AUC_(inf), AUC0-0.5, AUC0-2, AUC0-3, AUC0-4 parameters. Based on these statistics, the ratios of the geometric means for treatments and the corresponding 90% confidence intervals were calculated for the following contrasts:

-   -   Treatment A versus Treatment C (relative bioavailability under         fasting conditions)     -   Treatment B versus Treatment A (food effect for the test         formulation)

Summary-Conclusions:

Pharmacokinetic and Statistical Results of MPH ER Chewable Tablets 40 mg Versus Methylin™ 10 mg Chewable Tablets

Geometric 90% Confidence Mean Ratio Limits Intra-Sub MPH Test Reference (%) Lower Upper CV (%) C_(max) 12.1 15.1 80.0 76.3 83.9 11 (ng/mL) AUC_((0-t)) 107.4 122.7 87.6 84.9 90.4 7 (ng · h/mL) AUC_((0-inf)) 113.6 127.5 89.1 86.6 91.7 7 (ng · h/mL) These statistics were used to evaluate the performance of the test formulation in relation to the reference product and the test product as fed versus fasting. Pharmacokinetic and Statistical Results of MPH ER Chewable Tablets 40 mg, Fed Versus Fasting Study

Geometric 90% Confidence Mean Ratio Limits Intra-Sub MPH Fed Fasting (%) Lower Upper CV (%) C_(max) 12.6 12.1 104.1 99.4 108.9 11 (ng/mL) AUC_((0-t)) 129.6 107.5 120.6 117.0 124.3 7 (ng · h/mL) AUC_((0-inf)) 137.9 113.6 121.4 118.0 124.9 7 (ng · h/mL) Treatment A: Methylphenidate HCl Extended Release 40 mg chewable tablets—Fasting Treatment B: Methylphenidate HCl Extended Release 40 mg chewable tablets—Fed Treatment C: Methylin™ 10 mg chewable tablets—Fasting

Safety Results:

There were no deaths, Serious Adverse Events (SAEs), or other significant adverse events during the conduct of this study. None of the AEs had a significant impact on the safety of the subjects or on the integrity of the study results.

CONCLUSIONS

All treatments under either fasted or fed conditions were well tolerated by all subjects in the study. Based on the results of the study, the test product has similar maximum and peak absorption characteristics when administered under fasting and fed conditions. There is no significant food effect on the test product.

Methylphenidate HCl 40 mg ER chewable tablets produce a mean peak concentration 20% lower than b.i.d. administration of 20 mg of the Methylin™ 10 mg product. The total exposure is similar starting at approximately 4 hours.

All patents, patent publications, and other publications listed in this specification, as well as prior U.S. patent application Ser. No. 14/872,226, filed Oct. 1, 2015, which is a continuation of U.S. patent application Ser. No. 14/624,998, filed Feb. 18, 2015, now U.S. Pat. No. 9,180,100, which is a continuation of U.S. patent application Ser. No. 14/300,580, filed Jun. 10, 2014, now U.S. Pat. No. 8,999,386, prior International Patent Application No. PCT/US2013/054930, filed Aug. 14, 2013 and US Provisional Patent Application Nos. 61/774,783, filed Mar. 8, 2013 and 61/683,513, filed Aug. 15, 2012, are incorporated herein by reference. While the invention has been described with reference to a particularly preferred embodiment, it will be appreciated that modifications can be made without departing from the spirit of the invention. Such modifications are intended to fall within the scope of the appended claims. 

The invention claimed is:
 1. A method for treating a patient with a disorder treatable by methylphenidate, said method comprising providing said patient with an effective amount of a methylphenidate extended release chewable tablet which is a uniform solid dispersion comprising: (a) a sustained release racemic methylphenidate component comprising a water-insoluble, water-permeable, pH-independent barrier coated, racemic methylphenidate—ion exchange resin complex in a polymeric matrix, wherein said barrier coating which provides a sustained release profile to the racemic methylphenidate is over the racemic methylphenidate—ion exchange resin complex-matrix; (b) a first immediate release component which comprises an immediate release uncoated racemic methylphenidate—ion exchange resin complex; (c) a second immediate release racemic methylphenidate component which comprises an uncomplexed racemic methylphenidate acceptable salt thereof; wherein said first immediate release component (b) has a slower onset of release than (c); wherein about 50% w/w to about 90% w/w of the racemic methylphenidate active component is provided by the sustained release component based on the total amount of racemic methylphenidate in the tablet, and wherein said chewable tablet is capable of being divided and providing tablet portions which retain a therapeutically effective extended release profile, and a pharmacokinetic profile in which the methylphenidate has at least one of: a geometric mean for area under the curve (AUC)_(0-∞) of about 110 ng-hr/mL to about 140 ng-hr/mL and a geometric mean C_(max) of about 10 ng/mL to about 15 ng/mL, under fasted and fed conditions in adults following a single oral administration of a chewable tablet comprising the equivalent of 40 mg racemic methylphenidate HCl.
 2. The method according to claim 1, wherein said patient has been diagnosed with attention deficit hyperactivity disorder, postural orthostatic tachycardia syndrome, or narcolepsy.
 3. The method according to claim 1, wherein C_(max) is about 12 ng/mL to about 13 ng/mL.
 4. The method according to claim 1, wherein geometric mean AUC_(0-∞) is about 113 ng-hr/mL to about 138 ng-hr/mL.
 5. The method according to claim 1, the sustained release methylphenidate component provides about 60% w/w to about 80% w/w of the methylphenidate in the chewable tablet, based on the total amount of methylphenidate in the tablet.
 6. The method according to claim 1, wherein the immediate release uncoated racemic methylphenidate-ion exchange resin complex (b) and immediate release uncomplexed racemic methylphenidate (c) together comprise 20% w/w to about 40% w/w of the total racemic methylphenidate in the chewable tablet.
 7. The method according to claim 1, wherein the ratio of the immediate release uncoated methylphenidate—ion exchange resin complex (b) to immediate release component uncomplexed methylphenidate (c) is in the range of about 3:1 based on the total weight of immediate release components.
 8. The method according to claim 1, wherein the immediate release racemic methylphenidate—ion exchange resin complex is about 5% w/w to about 35% w/w of the total racemic methylphenidate in the chewable tablet.
 9. The method according to claim 1, wherein the immediate release uncomplexed racemic methylphenidate (c) is in the form of a pharmaceutically acceptable salt.
 10. The method according to claim 9, wherein the immediate release uncomplexed racemic methylphenidate (c) is in the form of racemic methylphenidate HCl.
 11. The method according to claim 1, wherein the immediate release uncomplexed racemic methylphenidate (c) is about 5% w/w to about 35% w/w of the total racemic methylphenidate in the chewable tablet, based on a calculation of total racemic methylphenidate in the tablet.
 12. The method according to claim 1, wherein the tablet comprises immediate release methylphenidate—ion exchange resin complex of (b) is about 15% w/w of the racemic methylphenidate in the tablet and a faster onset immediate release uncomplexed racemic methylphenidate (c) in about 15% w/w, based on a calculation of total racemic methylphenidate in the tablet.
 13. The method according to claim 1, wherein the tablet has a hardness in the range of about 8 kp to about 23 kp.
 14. The method according to claim 1, wherein the water insoluble, water-permeable, pH-independent barrier coating has an elongation factor range of about 150% to about 400% and is selected from (a) a cured, water-permeable, non-ionic, pH-independent barrier coating comprising polyvinylacetate, a stabilizer, and a plasticizer, applied as an aqueous dispersion; (b) an ionic, pH-independent, acrylic based coating comprising a polymer or copolymer comprising ethyl acrylate and methyl methacrylate applied as an aqueous dispersion; and (c) a solvent-based ethylcellulose coating, optionally with a plasticizer.
 15. The method according to claim 14, wherein the barrier coating over the methylphenidate-ion exchange resin complex-matrix of (a) is a cured, water-insoluble, water-permeable, non-ionic, pH-independent barrier coating comprises about 70 to about 90% w/w polyvinylacetate, a stabilizer, and about 2 to about 10% w/w of a plasticizer.
 16. The method according to claim 15, wherein the barrier coating layer is about 25% to about 35%, by weight, of the coated racemic methylphenidate—ion exchange resin complex-matrix.
 17. The method according to claim 1, wherein the polymeric matrix comprises polyvinylpyrolidone.
 18. The method according to claim 1, wherein the polymeric matrix further comprises a water-insoluble polymer.
 19. The method according to claim 16, wherein the barrier coating over the methylphenidate—ion exchange resin complex-matrix of (a) has a pH-independent, acrylic based coating, which said coating comprises a blend of (i) a poly(ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride) in a ratio of 1:2:0.1 and (ii) poly(ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride) in a ratio of 1:2:0.2.
 20. The method according to claim 1, wherein the chewable tablet further comprises a non-functional outer top coating layer.
 21. The method according to claim 1, wherein the chewable tablet further comprises one or more excipients.
 22. The method according to claim 1, wherein the chewable tablet has a pharmacokinetic profile for racemic methylphenidate comprising a single mean plasma concentration peak.
 23. The method according to claim 22, wherein the single mean plasma concentration peak is between about 4 hours to about 5.25 hours under fasted and fed conditions.
 24. The method according to claim 1, wherein said tablet comprises the equivalent of 40 mg racemic methylphenidate HCl.
 25. The method according to claim 1, wherein said tablet comprises the equivalent of 30 mg racemic methylphenidate HCl.
 26. The method according to claim 1, wherein said tablet comprises the equivalent of 20 mg racemic methylphenidate HCl.
 27. The method according to claim 1, wherein said tablet is scored.
 28. An extended release racemic methylphenidate chewable tablet, wherein said chewable tablet is a uniform solid dispersion comprising: (a) a sustained release, racemic methylphenidate component comprising a water-insoluble, water-permeable, pH-independent barrier coated, racemic methylphenidate-cation exchange resin complex which comprises: (i) a racemic methylphenidate-cation exchange resin complex comprising racemic methylphenidate and a pharmaceutically acceptable cation ion exchange resin, wherein the racemic methylphenidate is bound to the pharmaceutically acceptable cation exchange resin; (ii) a barrier coating over (i), wherein the barrier coating comprises a water-insoluble, water-permeable, pH-independent polymer and a plasticizer and the barrier coating is present in an amount of about 20% w/w to about 50% w/w % based on the weight of the racemic methylphenidate-cation exchange resin complex of (i) and provides a sustained release profile to the racemic methylphenidate; and wherein about 50% w/w to about 90% w/w of the racemic methylphenidate is provided by the sustained release component based on the total amount of racemic methylphenidate in the tablet; and (b) at least one immediate release racemic methylphenidate component which provides a release of the racemic methylphenidate in less than about 30 minutes as determined in an in vitro dissolution assay; wherein said chewable tablet is capable of being divided and providing tablet portions which retain a therapeutically effective extended release profile, and a pharmacokinetic profile in which the methylphenidate has at least one of: a geometric mean for area under the curve (AUC)_(0-∞) of about 110 ng-hr/mL to about 140 ng-hr/mL or a geometric mean C_(max) of about 10 ng/mL to about 15 ng/mL, under fasted conditions in adults following a single oral administration of a chewable tablet which comprises the equivalent of 40 mg racemic methylphenidate HCl.
 29. The extended release racemic methylphenidate chewable tablet according to claim 28, wherein the plasticizer is selected from propylene glycol, polyethylene glycol, dibutyl sebacate, propylene glycol, polyethylene glycol, polyvinyl alcohol, triethyl citrate, acetyl triethyl citrate, acetyl tributyl citrate, tributyl citrate, triacetin, 2-pyrrolidone, or mixtures thereof.
 30. The extended release racemic methylphenidate chewable tablet according to claim 28, wherein the plasticizer comprises triethyl citrate.
 31. The extended release racemic methylphenidate chewable tablet according to claim 28, wherein the water-insoluble, water-permeable, pH-independent polymer is present in an amount of about 70% to about 90% w/w, based on the weight of the final barrier coating layer.
 32. The extended release racemic methylphenidate chewable tablet according to claim 28, wherein the immediate release methylphenidate component (b) is uncoated racemic methylphenidate-cation exchange resin complex which comprises racemic methylphenidate bound to a pharmaceutically acceptable cation exchange resin.
 33. The extended release racemic methylphenidate chewable tablet according to claim 32, wherein the immediate release component (b) comprises about 20% w/w to about 40% w/w of the total racemic methylphenidate in the chewable tablet.
 34. The extended release racemic methylphenidate chewable tablet according to claim 28, wherein the sustained release methylphenidate component provides about 60% w/w to about 80% w/w of the methylphenidate in the chewable tablet, based on the total amount of methylphenidate in the chewable tablet.
 35. The extended release racemic methylphenidate chewable tablet according to claim 28, wherein the tablet has a hardness in the range of about 8 kp to about 23 kp.
 36. The tablet according to claim 28, wherein the in vitro dissolution assay is performed placing the tablet in 900 mL 0.4 M potassium phosphate buffer with 37° C.±5° C. with a USP paddle speed of 75 rpm.
 37. The tablet according to claim 28, wherein the tablet has a pharmacokinetic profile for racemic methylphenidate which comprises a single mean concentration peak.
 38. The extended release racemic methylphenidate chewable tablet according to claim 28, wherein the barrier coat has an elongation factor of at least 150% to about 400% as measured by a texture analyzer.
 39. The extended release racemic methylphenidate chewable tablet according to claim 38, wherein the barrier coat is selected from: (a) a cured, water-permeable, non-ionic, pH-independent barrier coating comprising polyvinylacetate, a stabilizer, and the plasticizer; (b) a pH-independent, acrylic based coating comprising a polymer or copolymer comprising ethyl acrylate and methyl methacrylate and a plasticizer; or (c) a water-permeable, non-ionic, pH-independent barrier coating comprising ethylcellulose and the plasticizer.
 40. The extended release racemic methylphenidate chewable tablet according to claim 28, wherein the plasticizer is about 2.5% to about 20% by weight of the coating. 